mirror of https://github.com/akuker/RASCSI.git
105 lines
3.2 KiB
C++
105 lines
3.2 KiB
C++
//---------------------------------------------------------------------------
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//
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// X68000 EMULATOR "XM6"
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//
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// Copyright (C) 2001-2006 ＰＩ．(ytanaka@ipc-tokai.or.jp)
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// Copyright (C) 2014-2020 GIMONS
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// Copyright (C) 2022 Uwe Seimet
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//
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//---------------------------------------------------------------------------
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#include "bus.h"
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using namespace std;
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//---------------------------------------------------------------------------
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//
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// Get the number of bytes for a command
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// TODO Add the byte count to the enum value/command name mapping and remove the comparisons
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//
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//---------------------------------------------------------------------------
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int BUS::GetCommandByteCount(uint8_t opcode)
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{
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if (opcode == 0x88 || opcode == 0x8A || opcode == 0x8F || opcode == 0x91 || opcode == 0x9E || opcode == 0x9F) {
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return 16;
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} else if (opcode == 0xA0) {
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return 12;
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} else if (opcode >= 0x20 && opcode <= 0x7D) {
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return 10;
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} else {
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return 6;
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}
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}
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//---------------------------------------------------------------------------
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//
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// Phase Acquisition
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//
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//---------------------------------------------------------------------------
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BUS::phase_t BUS::GetPhase()
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{
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// Selection Phase
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if (GetSEL()) {
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return phase_t::selection;
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}
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// Bus busy phase
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if (!GetBSY()) {
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return phase_t::busfree;
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}
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// Get target phase from bus signal line
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int mci = GetMSG() ? 0b100 : 0b000;
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mci |= GetCD() ? 0b010 : 0b000;
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mci |= GetIO() ? 0b001 : 0b000;
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return GetPhase(mci);
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}
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//---------------------------------------------------------------------------
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//
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// Determine Phase String phase enum
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//
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//---------------------------------------------------------------------------
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const char* BUS::GetPhaseStrRaw(phase_t current_phase) {
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const auto& it = phase_str_mapping.find(current_phase);
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return it != phase_str_mapping.end() ? it->second : "INVALID";
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}
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//---------------------------------------------------------------------------
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//
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// Phase Table
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// Reference Table 8: https://www.staff.uni-mainz.de/tacke/scsi/SCSI2-06.html
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// This determines the phase based upon the Msg, C/D and I/O signals.
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//
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//---------------------------------------------------------------------------
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const array<BUS::phase_t, 8> BUS::phase_table = {
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// | MSG|C/D|I/O |
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phase_t::dataout, // | 0 | 0 | 0 |
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phase_t::datain, // | 0 | 0 | 1 |
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phase_t::command, // | 0 | 1 | 0 |
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phase_t::status, // | 0 | 1 | 1 |
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phase_t::reserved, // | 1 | 0 | 0 |
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phase_t::reserved, // | 1 | 0 | 1 |
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phase_t::msgout, // | 1 | 1 | 0 |
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phase_t::msgin // | 1 | 1 | 1 |
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};
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//---------------------------------------------------------------------------
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//
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// Phase string to phase mapping
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//
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//---------------------------------------------------------------------------
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const unordered_map<BUS::phase_t, const char*> BUS::phase_str_mapping = {
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{ phase_t::busfree, "busfree" },
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{ phase_t::arbitration, "arbitration" },
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{ phase_t::selection, "selection" },
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{ phase_t::reselection, "reselection" },
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{ phase_t::command, "command" },
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{ phase_t::datain, "datain" },
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{ phase_t::dataout, "dataout" },
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{ phase_t::status, "status" },
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{ phase_t::msgin, "msgin" },
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{ phase_t::msgout, "msgout" },
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{ phase_t::reserved, "reserved" }
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};
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